2015 – 072 US EPA using secret pollution data to make laws.

Republican lawmakers are once again questioning the “secret science” used by the EPA to justify some of the costliest Clean Air Act regulations in history.

“The most expensive rules coming out of the EPA rely on secret science,” Sen. Jim Inhofe, an Oklahoma Republican, told FoxNews.com in a statement. “Americans deserve to have access to technical information and data being used to develop EPA rules that significantly impact their daily lives.”

Inhofe’s statement comes after Republicans grilled EPA Chief Administrator Gina McCarthy in a hearing last week over the agency’s use of nonpublic data to calculate the benefits of reducing air pollutants. The EPA “has a responsibility to be open and transparent with the people it serves, and whose money it spends,” Texas Republican Rep. Lamar Smith, House science committee chairman, said during the hearing.

President Barack Obama’s EPA regulatory agenda has imposed nearly $300 billion in costs, according to data from the American Action Forum, mostly from rules being promulgated under the Clean Air Act that rely on non-public scientific data.

To counteract the EPA’s regulatory agenda, Republicans passed the Secret Science Reform Act in the House last March. The bill would prevent the EPA from basing regulations on scientific data that’s not publicly available. So far, the EPA has pushed back against attempts to make its scientific data public.

“The EPA totally supports both transparency as well as a strong peer-reviewed independent science process, but the bill I’m afraid I don’t think will get us there,” McCarthy said during last week’s hearing.

“I don’t actually need the raw data in order to develop science, that’s not how it’s done,” she added. “I do not know of what value raw data is to the general public.”

EPA’s Clean Air Act regulations largely rely on data from two studies from the 1990s. The data from these studies, however, have not been made publicly available, and some researchers who have sought the data have been rebuffed by the study’s authors.

One of the studies, a 1993 study from Harvard University, linked air pollution to premature death in six cities across the United States. The study specifically linked fine particulate matter, or PM, to premature death — a finding the EPA has used as a crowbar to justify massive regulations.

So far, the costliest rule finalized by the EPA is its greenhouse gas tailpipe standards for light-duty vehicles. That rule is projected to cost $10.8 billion annually and carry some $156 billion in total costs. The agency, however, argues the rule will yield $451 in net benefits from fuel savings, carbon dioxide emissions cuts and from cutting air pollutants.